// SHA-256 alghorithm implemented by Angel Marin, http://anmar.eu.org/projects/jssha2/
var chrsz = 8;
function safe_add (x, y) {
  var lsw = (x & 0xFFFF) + (y & 0xFFFF);
  var msw = (x >> 16) + (y >> 16) + (lsw >> 16);
  return (msw << 16) | (lsw & 0xFFFF);
}
function S (X, n) {return ( X >>> n ) | (X << (32 - n));}
function R (X, n) {return ( X >>> n );}
function Ch(x, y, z) {return ((x & y) ^ ((~x) & z));}
function Maj(x, y, z) {return ((x & y) ^ (x & z) ^ (y & z));}
function Sigma0256(x) {return (S(x, 2) ^ S(x, 13) ^ S(x, 22));}
function Sigma1256(x) {return (S(x, 6) ^ S(x, 11) ^ S(x, 25));}
function Gamma0256(x) {return (S(x, 7) ^ S(x, 18) ^ R(x, 3));}
function Gamma1256(x) {return (S(x, 17) ^ S(x, 19) ^ R(x, 10));}
function core_sha256 (m, l) {
    var K = new Array(0x428A2F98,0x71374491,0xB5C0FBCF,0xE9B5DBA5,0x3956C25B,0x59F111F1,0x923F82A4,0xAB1C5ED5,0xD807AA98,0x12835B01,0x243185BE,0x550C7DC3,0x72BE5D74,0x80DEB1FE,0x9BDC06A7,0xC19BF174,0xE49B69C1,0xEFBE4786,0xFC19DC6,0x240CA1CC,0x2DE92C6F,0x4A7484AA,0x5CB0A9DC,0x76F988DA,0x983E5152,0xA831C66D,0xB00327C8,0xBF597FC7,0xC6E00BF3,0xD5A79147,0x6CA6351,0x14292967,0x27B70A85,0x2E1B2138,0x4D2C6DFC,0x53380D13,0x650A7354,0x766A0ABB,0x81C2C92E,0x92722C85,0xA2BFE8A1,0xA81A664B,0xC24B8B70,0xC76C51A3,0xD192E819,0xD6990624,0xF40E3585,0x106AA070,0x19A4C116,0x1E376C08,0x2748774C,0x34B0BCB5,0x391C0CB3,0x4ED8AA4A,0x5B9CCA4F,0x682E6FF3,0x748F82EE,0x78A5636F,0x84C87814,0x8CC70208,0x90BEFFFA,0xA4506CEB,0xBEF9A3F7,0xC67178F2);
    var HASH = new Array(0x6A09E667, 0xBB67AE85, 0x3C6EF372, 0xA54FF53A, 0x510E527F, 0x9B05688C, 0x1F83D9AB, 0x5BE0CD19);
    var W = new Array(64);
    var a, b, c, d, e, f, g, h, i, j;
    var T1, T2;
    m[l >> 5] |= 0x80 << (24 - l % 32);
    m[((l + 64 >> 9) << 4) + 15] = l;
    for ( var i = 0; i<m.length; i+=16 ) {
        a = HASH[0]; b = HASH[1]; c = HASH[2]; d = HASH[3]; e = HASH[4]; f = HASH[5]; g = HASH[6]; h = HASH[7];
        for ( var j = 0; j<64; j++) {
            if (j < 16) W[j] = m[j + i];
            else W[j] = safe_add(safe_add(safe_add(Gamma1256(W[j - 2]), W[j - 7]), Gamma0256(W[j - 15])), W[j - 16]);
            T1 = safe_add(safe_add(safe_add(safe_add(h, Sigma1256(e)), Ch(e, f, g)), K[j]), W[j]);
            T2 = safe_add(Sigma0256(a), Maj(a, b, c));
            h = g; g = f; f = e; e = safe_add(d, T1); d = c; c = b; b = a; a = safe_add(T1, T2);
        }
        HASH[0] = safe_add(a, HASH[0]); HASH[1] = safe_add(b, HASH[1]); HASH[2] = safe_add(c, HASH[2]); HASH[3] = safe_add(d, HASH[3]); HASH[4] = safe_add(e, HASH[4]); HASH[5] = safe_add(f, HASH[5]); HASH[6] = safe_add(g, HASH[6]); HASH[7] = safe_add(h, HASH[7]);
    }
    return HASH;
}

function str2binb (str) {
  var bin = Array();
  var mask = (1 << chrsz) - 1;
  for(var i = 0; i < str.length * chrsz; i += chrsz)
    bin[i>>5] |= (str.charCodeAt(i / chrsz) & mask) << (24 - i%32);
  return bin;
}
function binb2hex (binarray) {
  var hexcase = 0; /* hex output format. 0 - lowercase; 1 - uppercase */
  var hex_tab = hexcase ? "0123456789ABCDEF" : "0123456789abcdef";
  var str = "";
  for (var i = 0; i < binarray.length * 4; i++) {
    str += hex_tab.charAt((binarray[i>>2] >> ((3 - i%4)*8+4)) & 0xF) + hex_tab.charAt((binarray[i>>2] >> ((3 - i%4)*8  )) & 0xF);
  }
  return str;
}

function hex_sha256(s){return binb2hex(core_sha256(str2binb(s),s.length * chrsz));}


  function sha2password(source, passwordtype, passwordlength)
  {
    if (passwordlength < 4) passwordlength = 4;

    source = hex_sha256(source+passwordlength);
    
    var tabsmall = "";
    var tabdigits = "";
    var tabbig = "";
    var tabspec = "";
    var tab = "";                   

    for (var i = "a".charCodeAt(0); i <= "z".charCodeAt(0); i++)
      tabsmall +=  String.fromCharCode(i);

    for (var i = "0".charCodeAt(0); i <= "9".charCodeAt(0); i++)
      tabdigits +=  String.fromCharCode(i);

    for (var i = "A".charCodeAt(0); i <= "Z".charCodeAt(0); i++)
      tabbig +=  String.fromCharCode(i);

    tabspec += '~!@#$%^&*()_+=-[]{}":;><,.';

    tab = tabsmall+tabdigits;

    if (passwordtype > 0)
      tab += tabbig;

    if (passwordtype > 1)
      tab += tabspec;

    var res = "";
    var pos = 0;
    var target = 0;
    var L = passwordlength;

    while (res.length < L)
    {
      pos = pos % source.length;
      var sourcechar = source.charAt(pos);

      for (var i = 0; i < source.charCodeAt(0); i++)
      {
        pos = (pos + 1) % source.length;
        target = (target + source.charCodeAt(pos)) % tab.length;
        target += 1;
      }

      res += tab.charAt(target);
      source = hex_sha256(source + res);
    }

    var possmall = hex_sha256(source).charCodeAt(0) % L;

    var posdigit = hex_sha256(source).charCodeAt(1) % L;
    while (posdigit == possmall)
      possmall = (possmall + 1) % L;

    var posbig   = hex_sha256(source).charCodeAt(2) % L;
    while ((posbig == possmall) | (posbig == posdigit))
      posbig = (posbig + 1) % L;

    var posspec  = hex_sha256(source).charCodeAt(3) % L;
    while ((posspec == possmall) | (posspec == posdigit) | (posspec == posbig))
      posspec = (posspec + 1) % L;

    var sum = 0;

    for (var i = 0; i < 4; i++)
      sum += hex_sha256(source).charCodeAt(i);
    res = res.substring(0, possmall) + tabsmall.charAt(sum % tabsmall.length) + res.substring(possmall+1, res.length);
 
    for (var i = 4; i < 8; i++)
      sum += hex_sha256(source).charCodeAt(i);
    res = res.substring(0, posdigit) + tabdigits.charAt(sum % tabdigits.length) + res.substring(posdigit+1, res.length);

    if (passwordtype > 0)
    {
      for (var i = 8; i < 12; i++)
        sum += hex_sha256(source).charCodeAt(i);
      res = res.substring(0, posbig) + tabbig.charAt(sum % tabbig.length) + res.substring(posbig+1, res.length);
    }

    if (passwordtype > 1)
    {
      for (var i = 12; i < 16; i++)
        sum += hex_sha256(source).charCodeAt(i);
      res = res.substring(0, posspec) + tabspec.charAt(sum % tabspec.length) + res.substring(posspec+1, res.length);
    }

    return res;
  }